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isotopes &compounds formulas and equations (compounds (2) compounds…
isotopes &compounds formulas and equations
isotopes
2)same atomic number but different mass number
3)carbon 12 ; 6 protons 6 electrons 6 neutrons and carbon 13 which had 6 protons 6 electrons and 7 neutrons
4)relative atomic mass is an average mass taking into account the different masses and abundances of all the isotopes that make up the elements
1)isotopes are defined as DIFFRENT FORMS OF THE SAME ELEMENT WHICH HAVE THE SAME NUMBER OF PROTONS BUT A DIFFRENT NUMBER OF NUTRONS
5)relative atomic mass (Ar)= sun of 9isotope abundance x isotope mass number)/ sum of abundance of all he isotopes
compounds
2) compounds are substances formed from 2 or more elements the atom of each are in fixed proportions held together by a chemical bond
3) making bonds involves atoms giving away taking or sharing a electron only electrons are effected the nuclei is not effected
1)when elements react atoms combine with other atoms to form compouds
4)difficult to separate the original element of a compound out again a chemical reaction is needed
atoms join together to make a compound
5)compound made of a metal and non metal consists of ions .the metal atoms lose electrons to form a positive ion and the non metal atoms gain electrons to form negative ions .
6) a compound formed from a non metal consists of molecules each atom shares a electron with another atom this is called covalent bonding
7)properties of a compound are usually totally different from the properties of the original elements.
a formula shows what atoms are in a compound
2) here's another example the formula of sulphur acid is a h2so4 so each molecule contains 2 hydrogen atoms 1 sulphur atom and 4 oxygen atoms
3) might be brackets in the formula eg calcium hydroxide is a Ca(OH)2 the little number out side the bracket applies to everything inside the bracket
1) eg carbon dioxide co2 is a compound formed from a chemical reaction between carbon and oxygen ot contains 1 carbon atom and 2 oxygen atoms
examples CARBON DIOXIDE C02 2 AMMONIA NH3 WATER H20
Chemical changes are shown using chemical equations
methane + oxygen -> carbon dioxide+water
the molecules on the left hand side of the equation are called the reactants because they will react with each other
show a chemical reaction by a word equation
the molecules on the right hand side are called products what's been made
symbol equations
magnesium + oxygen 2mg+o2 --> magnesium oxide 2mgo
chemical changes can be shown using symbols to replace words they show the symbols or formulas of the reactants and products